1. Field of the Invention
The invention relates to a printer for printing data output by a device, such as a computer, on a print medium. More particularly, the invention relates to a printer capable of opening and shutting its upper frame relative to its lower frame in order to easily handle the print medium.
2. Description of Related Art
Conventionally known is a printer having a frame which can be opened and shut in order to exchange the print paper or remove jammed print paper.
In such a printer, an upper frame, on which a print head is arranged, is pivotably connected, at the side of the upper frame away from the print head, with a lower frame on which a platen and a feeding device are arranged. Under normal circumstances, that is, during printing, the upper frame is positioned on the lower frame by a lock mechanism such that the print head confronts with the platen. The print paper is intermittently fed between the print head and the platen by the feeding device and is printed by the print head.
If the lock mechanism is released, for exchanging the print paper and/or removing jammed paper, the upper frame is rotated around the rotating axis by the action of a spring that extends between the upper frame and the lower frame. As a result, the print head is separated from the platen with a big circular arc movement. Under such a condition, it is possible for the operator's hands to be inserted into the feeding device, between the platen of the lower frame and the rotating axis line of the upper frame, to remove the paper and/or to set a new paper in the feeding device. A printer so structured is disclosed in European Patent Application No. 448 519.
In the above described conventional printer, it is difficult to handle the paper at the time of exchanging the paper and removing the jammed paper because the operator must put his/her hands into the feeding device through the narrow gap between the upper frame in the opened condition and the platen. If the space around the feeding device is widened, the above problem will be solved. Such a solution, however, causes another problem in that it enlarges the whole printing device.
Further, it was dangerous to the operator, who exchanges the paper and/or removes the jammed paper, because the upper frame rotates to an open position by the action of the spring when the lock mechanism is released. Moreover, there is a further problem in that the opening and shutting mechanism, including the spring, needs to be quite large because of the considerable biasing power needed for opening the upper frame.
Further, in general printers, a motor to move the print head in the printing line direction and a motor to drive the feeding device were usually mounted to the side walls of the upper or the lower frame. Moreover, a circuit substrate, to control the print head and the motors, was usually arranged in a lower or rear portion of the upper and lower frame. Therefore, the printer was enlarged and the feeding path of the print paper was lengthened. This further deteriorated the operator's ability to handle the print paper.